The present invention relates to water distributing apparatus and more particularly to a water sprinkler system for use in uniformly wetting a roof structure.
References known to the present applicant and believed to be relevant to the present invention include the following U.S. Pat. Nos. 1,831,880 issued to Pierce; 2,865,674 issued to Jelmeland; 3,587,972 issued to Weeth; and 3,633,826 issued to Baker. The Pierce patent teaches a fire protection and roof cooling arrangement comprising basically a length of perforated pipe positioned on the ridge of a roof. The Jelmeland patent also teaches a roof cooling and fire prevention system in which somewhat conventional spray nozzles are positioned along the eaves of a roof to provide a water spray reaching all the way to the roof ridge. This patent also recognizes that in general excess amounts of water must be sprayed onto a roof to fully wet it with the result that much water runs off. The Jelmeland patent includes a recirculating pump system to avoid wasting the runoff water.
The patents to Weeth and Baker each provide apparatus for distribution of water in irrigation or lawn sprinkling systems. In each of these patents, a generally vertically extending flexible tube or hose is used as a discharge nozzle from a main water conduit to distribute irrigation water over as large a ground surface as possible. The normal reaction force produced by water flowing from the nozzle causes the flexible tube or hose in each of these patents to rotate in a generally circular pattern with the end of the hose directed at a fairly high angle, on the order of 45.degree., to provide maximum distribution of the water. In the Baker patent, it is also taught that splitting of the end of the rubber tube will break up the flow of water from the nozzle into a spray of small water droplets more desirable in the lawn sprinkling situation.
As taught by the first two above referenced patents, the sprinkling of water on a building roof will aid in cooling the entire structure. As can also be seen from those patents, the previously known systems tend to distribute much more water onto the roof structure than is actually needed for proper wetting. The perforated pipe arrangement taught by Pierce tends to produce a large number of distinct rivulets of water extending from each pipe perforation to the roof edge with dry roof areas in between. The sprinkler arrangement of Jelmeland breaks the water up into small droplets which are randomly distributed and therefore can provide essentially complete wetting of the roof. However, such a sprinkler arrangement is inefficient, especially if windy conditions are considered. The water droplets which must travel a great distance through the air before striking the roof may partly evaporate while in the air and tend to be carried completely away from the roof depending on the ambient wind velocity. As illustrated by the drawings in that patent, a considerable amount of the spray will extend beyond the roof edges to insure that the entire roof structure is wet. Excess water is also applied to be sure of complete wetting and then the excess is collected and recirculated.
Another problem found in these prior systems is that relatively high water supply pressure must be provided to the sprinkler head. For example, in the Jelmeland device, pressure must be sufficient to break the water into a fine mist and propel the mist to the roof ridge. In the Weeth and Baker devices the flexible tube is relatively stiff, and relatively high water pressure is required to cause the desired rotation.
It can be seen, therefore, that it is desirable to provide a system for wetting a roof structure to aid in cooling the structure, thereby reducing the cost of air conditioning the structure in warm climates. It can also be seen that it is desirable to provide uniform wetting of a roof structure and to do so using the least amount of water and at relatively low pressure. While it is desirable to uniformly distribute water on the roof structure, it can be seen that it is not desirable to break the water up into small droplets and spray them over long distances to the roof surface since windy conditions can cause considerable loss of water when such arrangment is employed.